Process of making halogenated indigo-white.



UNITED STATES PATENT OFFICE.

PAUL ERWIN OBERREIT, OF LUDWIGSHAFEN-ON-THE-RHINE, GERMANY, ASSIGNOR TOBADISCHE ANILIN & SODA FABRlK, OF LUDWIGSHAFEN- ON-THE-RHINE, GERMANY, ACORPORATION.

No. 835,462. Specification of Letters Patent. Patented Nov. 6, 1906.

Application filed April 17, 1908- Serial No. 312,210.

' To all whom it may concern.-

Be it known that 1, PAUL ERWIN OBERREIT, doctor of philosophyandchemist, a subject of the King of Saxony, residing atLudwigshafen-on-the-Rhine, in the Kingdom of Bavaria, German Empire,have invented" new and useful Improvements in- Process for theProduction of Halogenated Indigo-White, of which the followin 1s aspecification.

My invention re ates to the production of halogenated indi o-white fromhalogenated indigo. It is well own that bromindigo and chlorindigo andtheir homologues can be converted into the cones onding indigo-whitecompounds by means reducing agents, such as are employed in thereduction of indigo to indigo-white; but these reducing agentswhen usedfor reducing halogenated ind' 0 have the disadvantage that they remove te halogen to some extent, causing the production of ordinary indi0-white mixed with halogenated indigo-w to. -I have discovered thathalogenated indigo can be converted into thev cor'respondin halogenatedindigo-white by acting u on tie said halogenated indigo with indigo-w'te. It is preferable to make use of indigobite in caustic-sodasolution. When working according to this process, halogenatedindigo-White is obtained in solution, while indigo is precipitated andcan be removed by filtration.

The following examples will serve to further illustrate the nature of myinvention and how it can be carried into practical efiect; but myinvention is not confined to these examples, and it is to be understoodthat other halogenated indigo can be treatedina similar way. The partsare by weight.

Example .1 Warm to a temperature of from eighty (80) to one hundred(100) degrees centigrade one hundred (100) parts of twenty (20) percent. indigo-white solution which also contains five er cent. of causticsoda and while stirring a d twenty parts of bromindigo. Continue stirrinfor from three (3) to four (4) hours, and t en filter ofi the indigowhich has been recipitated. The solution of bromindigo-w 'te which isthus obtained can be used directly for dyeing.

Example 2: Stir fifty (50) parts of orthotolyl indigo-white with onethousand (1,000) arts of water which-is free from dissolved air and addsixty (60) parts of a thirty-five per cent. caustic-soda solution. Assoon as the indigo-white is dissolved Warm to a tem erature of fromsixty (60) to seventy (70) egrees centigrade, and while continuallystirring add fifty-six (56) parts of chlorortho-tolyl indigo. Stir fortwo -2) hours,

which has separated out. ,M

Now what I claim is V 1 The process for the production of halogenatedindigo-whiteby reducing halogenated indigo by means of indigo-White.

2. The process for the production of halogenate'd indigo-white byreducing halogenated indigo by means of indigo-white in caustic-sodasolution.

In testimony whereof I have hereunto set witnesses.

PAUL ERWIN OBERREIT. Witnesses:

J. Auto. LLOYD,

Jos. H. LEUTE.

and then filter oil the ortho-tolyl indigo my hand in the. presenceoftwo subscribing

